Hop extracts (instead of whole hops) have been used in brewing beer for a number of years. The considerations are several fold. When whole hops are added to the kettle, the yield of isohumulone in the finished product is extremely poor (20-25% based on humulone added). However, the utilization of pure isohumulones from a pre-isomerized extract added post kettle is known to be extremely high, 70-90%. Therefore, it is highly advantageous to produce pre-isomerized and purified isohumulones for such post kettle addition. In order to use isohumulones for post kettle additions and retain clarity, a high degree of purity is mandatory. Those components of a pre-isomerized extract such as lupulones, waxes and other beer insoluble residues cause substantial turbidity when added post kettle. The concentration of these insoluble ingredients in many commercial isohumulone preparations limit the concentration which may be added post kettle.
It is known that commercial isohumulones of approximately 80% purity cannot be added post kettle in amounts exceeding approximately 10-15 ppm of isohumulone without substantial increase in turbidity of the finished product. On the other hand, 30-40 ppm of isohumulone of high purity, 90%+, can be added post kettle with insignificant increase in turbidity. Furthermore, it is known that impure isohumulones, when added post kettle, may cause gushing or rapid carbon dioxide release from beer.
In this invention, 20-75% of the isohumulones are extracted from the pre-isomerized extract and added post kettle but in a purity so high (at least 90%) that increase in turbidity is minimal. Furthermore, all the remaining isohumulones, plus all other residual hop material in the pre-isomerized extract is added to the kettle so that nothing is wasted and the total hop character is retained.
Retaining "the total hop character" is critical. A customer's continuing selection of a particular brand of beer is based on highly subjective considerations. The customer, consciously or unconsciously, is swayed by taste, odor, and appearance, especially clarity and foam "cling". Taste and odor are controlled by the brewing process and the brewing ingredients. Foam properties are strongly influenced by isohumulones. Similarly, one of the primary taste-controlling ingredients is of course the hop, and particularly its content of resins and oils. A beer drinker tends to choose the same brand of beer, time after time, because of the reproduction of taste, odor, and foam. Brew masters are well aware of this and for this reason make great efforts to preserve identity of these features from brew to brew. The instant invention greatly facilitates the preservation of brew identity and provides clarity, light stability, and excellent foam stability and cling in the final beer.